On Tue, 8 Oct 1996, John F. Woods wrote:

> This isn't really a NetBSD question, but this group may know the
> answer to this anyway.  I have been seeing "stray interrupt 7"
> messages on my PC when I access tty02 and tty03 (PC COM3 and COM4).  I

> gather that IRQ7 is what the PC interrupt controller chip generates
> when it sees a glitch on an IRQ line.  I have changed the motherboard

Yes.  If the PIC cannot determine the source of an interrupt (the IRQ line
is not asserted long enough), it will generate a fake IRQ7.  Consult your
Intel 8259 data sheets for more information.  I left mine at home.

> Does anyone have any experience with a similar problem, or have any
> more systematic approach than to try to obtain replacements for all
> the cards?  Is there a DOS program that can be used to track this down

I have an internal Intel FaxModem that does the same thing whenever the
tty device is closed.  So whenever a pppd or tip session ends, "stray
interrupt 7" appears on the console.  However, I have determined that in
this case it's harmless.  I have never lost data over this problem. 

If the message is only appearing upon opening or closing the device, I 
don't see much cause for worry.